In view of improving fuel consumption and reducing toxic substance from exhaust gas, a fuel injection valve is demanded to enhance accuracy in fuel injection control. According to WO 96/37698, for example, a fuel injection valve has a structure, in which a valve element is manipulated by utilizing fuel pressure to open and close a nozzle hole. In the structure of WO 96/37698, a control performance of fuel injection can be enhanced.
Specifically, the fuel injection valve of WO 96/37698 includes a main body, a valve element, and a piston. The main body has a nozzle hole and a compression chamber. The compression chamber accumulates fuel to pressurize the fuel therein. The valve element is axially movable in the main body. The valve element has a pressure-receiving portion via which the valve element is applied with pressure of fuel in the compression chamber. The piston pressurizes fuel in the compression chamber to apply pressure of the fuel to the pressure-receiving portion, thereby manipulating the valve element to open the nozzle hole. Thus, the fuel injection valve controls fuel injection.
In the structure of the fuel injection valve of WO 96/37698, the compression chamber accommodates components such as a string for biasing the piston. Therefore, the compression chamber needs a sufficient volume for accommodating components such as the spring. However, when the piston pressurizes fuel in a compression chamber with a large volume, the piston cannot promptly pressurize fuel in the compression chamber. Therefore, it is hard to enhance response of the valve element.